AI agent vulnerability · LiteLLM

CVE-2026-12773: LiteLLM: MCP Proxy Has Improper Authentication

mediumCVSS 4.0 5.5 · 3.1 7.3GHSA-4jcj-7x88-m979

A weakness has been identified in BerriAI litellm up to 1.59.8. Affected is the function UserAPIKeyAuth of the file litellm/proxy/experimental/mcpserver/auth/userapikeyauthmcp.py of the component MCP Proxy. Executing a manipulation can lead to improper authentication. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks.

Published Jun 21, 2026 · Updated Sep 10, 2026

Affected packages

litellm

Ecosystem: PyPI
Affected: < 1.84.0
Fixed in: 1.84.0
Check: pip show litellm

Advisory details

From the GitHub Advisory Database (CC BY 4.0).

A weakness has been identified in BerriAI litellm up to 1.59.8. Affected is the function UserAPIKeyAuth of the file litellm/proxy/_experimental/mcp_server/auth/user_api_key_auth_mcp.py of the component MCP Proxy. Executing a manipulation can lead to improper authentication. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure.

References

How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology

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